HU196156B - Process for producing concrete, reinforced concrete and stressed reinforced concrete building elements and constructions - Google Patents

Abstract

Portland cement of 550 pc quality is added to the slightly plastic basic concrete mixt. During the heat treatment the surrounding air is kept at min. 30 deg.C and the plasticity is adjusted with liq. additives.

Description

The present invention relates to a process for the production of concrete, reinforced concrete and prestressed reinforced concrete building elements and structures which are formed by accelerated concrete reinforcement.

Methods of accelerating strength in pre-fabricated concrete, reinforced concrete and prestressed reinforced concrete elements have long been known. Some of the different methods and equipment for concrete reinforcement are based on steam and on the other hand they are based on electrical heat transfer.

Steaming processes include those described in 2.432.371. No. 2,444,544. No. and 2.454.26. French Patent Specification No. 1,139,107; The methods described in German Patent Publication No. 1, p.

The common feature of these solutions is to increase the strength of the concrete by pre-curing the concrete and, with different chemical additives, to shorten the setting time of the crude concrete using, of course, equipment and service units belonging to different technological processes.

Accelerating the setting of concrete can be accomplished by carbonization and vacuum, as described in 2.106.937. It is also apparent from U.S. Patent No. 5,198, issued to the Federal Republic of Germany. The device, with the control of temperature sensors, utilizes the heat of hydration to achieve economical prefabrication. According to the patent, the process is preferably used for the production of plaster-based elements.

One of the methods of forming concrete elements is described in U.S. Patent No. 2,106.937. U.S. Patent No. 4,600,128, where the curing acceleration of precast concrete elements is achieved by heating the formwork.

The common feature of the solutions is that they can always be implemented with prefabricated, operational technology, accelerating the thermo-maturation of the elements and at the same time increasing their strength. The use of various additional structural elements is essential for carrying out the processes. For successful implementation of the technological process, eg. control units etc. it is absolutely necessary. Because of their complexity, these solutions are not, or only very uneconomically feasible, for on-site concreting work on structures, possibly with additional service aids.

It is an object of the present invention to provide a method which, while retaining the useful results of the known solutions and their proper combination, can produce economical concrete elements requiring a short formwork time, which can be produced by simple tooling.

The inventive idea is based on the recognition that concrete elements with a high specific surface area have a 50% efficiency of 24 hours strength (required for formwork and transport), without artificial heat aging and deterioration of the concrete structure if at least 30 ° C. at ambient temperature - keeping the concrete fresh using the hydration heat as well. This recognition greatly facilitates the construction of the best possible structural concrete by avoiding the deterioration of the structure due to the physical and chemical effects of artificial heat aging, which results in a reduced strength of steamed concrete for 28 days and less than naturally hardened concrete.

In accordance with the object, the process for producing concrete, reinforced concrete and prestressed reinforced concrete building blocks and structures, which are formed by accelerated concrete consolidation, is based on the use of low-plastic-plastic consistency using 550 pc quality Portland cement adapted to the function of the structure. During the setting, the ambient air is kept at a temperature of at least 30 ° C until the formwork is matured, and the strength of the concrete is altered by plasticity, e.g. increase with the addition of a lubricant additive.

A further feature of the process may be that the elements are made from Portland cement having a specific surface area greater than 500 m ¹ / kg and the desired ambient air temperature is formed by a closed air space, e.g. natural heat application foil.

Alternatively, in case of prefabrication, the thickness of the elements is selected at least 15 cm, the elements are placed in a heat-insulated template and the required ambient temperature is created by utilizing the hydration heat.

The process according to the invention has significant advantages. The process is suitable for the production of both prefabricated and monolithic elements. It can be used in the field of monolithic concreting in areas where construction technology requires a high initial strength, such as concrete. tunnel formwork slabs, freeboard bridge construction, etc.

It is also an absolute benefit that the 24 hour strength of the concrete element produced by the process reaches the 50% required for formwork and transport without damaging the concrete structure. Its cost-effectiveness is indisputable, as it reduces the cost of the maturation equipment and the cost of steam or electricity for solidification.

The invention will now be described in more detail with reference to the following examples.

Example 1

550 pc quality cement, 24 mm maximum particle size, I.o. Concrete characterized by an additive, two types of cement content and a weak plastic - plastic consistency boundary was prepared and stored in a temperature of 30 ° C. Their 1-day strength compared to the 28-day is:

kg / m ³ 275 cement 390 520 cube strength MPa 28 days 1 day relative solid- 29 39 44 % Bending tensile strength, 50 55 60 MPa, 28 days 1 day relative solid- 5 6.4 7 % (three point cow) 56 59 70

Example 2

The concrete in Example 1 was prepared with a cement content of 450 kg / m ³ , with a low plastic consistency and, after preparation, placed in thermal insulation formwork. The temperature of the concrete is approx. 20

196.156 ° C. Compared to 28-day concrete strength, 1-day cube strength was 55%, while that of uninsulated formwork was only 42%. The temperature of the concrete was 10-14 ° C higher than the ambient air, while the temperature of the uninsulated concrete was 6-8 ° C higher.

Example 3

With 550 pc quality cement, 270 kg / m ³ cement content, plastic consistency, djj _iax = 24 mm maximum mesh size II. She. 15 cm thick wall panel was made with additive in insulated formwork. The panels were stored outdoors while the air temperature varied between 25 and 15 ° C. The temperature of the concrete is 30 ° C for 4 hours and approx. It increased to 38 ° C, and this temperature decreased by only 3-4 ° C after 24 hours. The 24-hour relative strength of concrete (cured) at 20 ° C (standard) over 24 hours was found to be 55-60%.

The concrete element produced by the process of the present invention is suitable for the construction of any civil engineering or civil engineering structure which is prefabricated or on site.

Claims (3)

PATENT CLAIMS A process for the production of concrete, reinforced concrete and prestressed reinforced concrete building elements and structures by accelerated concrete consolidation, characterized in that the elements are made with a quantity of 550 pc grade Portland cement adapted to the function of the structure, with low ductile, plastic consistency. without artificial heat maturation, the ambient air is maintained at a temperature of at least 30 ° C until the formwork is formed; increase with the addition of a flux additive j 5. Method according to claim 1, characterized in that the elements are made of Portland cement with a specific surface area greater than 500 m ^J / kg and the desired ambient air temperature is formed by a closed air space, e.g. natural heat-applied foil. Method according to claim 1 or 2, characterized in that, in the case of pre-fabrication, the thickness of the elements is selected to be at least 15 cm, the elements are placed in a heat-insulated template and the required ambient temperature is achieved using the hydration heat.